1. Field of the Invention
This invention relates to linear and crosslinked polymeric compositions composed of repeating segmental residues having alternating ether and amide linkages.
2. Description of the Prior Art
It is known that a 2-oxazoline will react with a compound containing an active hydrogen group of sufficient acid strength in a ring opening type mechanism to provide a secondary amide. Active hydrogen compounds reported in the prior art capable of undergoing the indicated reaction include carboxylic acids, thiols and phenols, the latter embracing the various phenol-aldehyde or phenol-ketone condensates containing a plurality of aromatic hydroxyl groups. The reaction of a novalak in this manner to prepare a polyamine precursor is exemplified in U.S. Pat. No. 4,195,154.
Beyond preparing amides in accordance with this chemistry, the prior art also teaches the preparation of polymeric compositions resulting when the respective reactants are polyfunctional in nature. Thus the preparation of poly (thioether-amide) type polymeric composition is reported, for example, in J. Polym. Sci., Lett. Edit., 18, 761 (1980). Dicarboxylic acids and a bis-oxazoline likewise react in the step-growth polymerization reaction to provide a poly (ester-amide) type polymeric composition. The latter investigatory prior art can be found in J. Polym. Sci., Polym. Lett. Edit., 4 25 (1966).
The aforesaid poly(thioether-amide) as well as the poly(ester-amide) polymeric compositions have not gained commercial acceptance in spite of their potentially interesting structural characteristics. This is so for presumably a variety of reasons. For instance, the general unavailability of the polythiols and the odor problem associated with their use represent serious drawbacks in the commercial development of polymeric compositions of this type.
The diacids, on the other hand, are commodity items and more facilely undergo the underlying ring opening reaction. But the diacids, particularly the desirable aromatics, suffer because of their high melting points thereby making melt processing difficult if not infeasible.